The purpose of this project is to determine behavioral differences in operant responding, learning, and retention for rodents as a function of age. To study the genetic aspects of operant performance and retention, inbred mice are utilized. Animals are motivated during operant conditioning by a light contingency, dark contingency, or food reward. For Wistar rats, the response rate on fixed interval schedules of food reward are studied for young and aged groups. To precisely analyze the learning process, a Stone 14-unit multiple-T maze is utilized. By charting the exact path of the animal through the maze, the learning and retention process is studied in great detail.